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Topic Review (Newest First)

05-15-2014 06:04 AM

SVAuspicious

Re: AIS / Marine Traffic

Quote:

Originally Posted by 34crealock

Do you suppose the software in the AIS is just coming up with wildly high SWR.

Very unlikely. If it was a software problem there would be more widespread reports of similar issues.

It shouldn't be hard to get VSWR well below 2:1. Any local ham (check ARRL.org for clubs in your area) with a VHF SWR meter can help you. An antenna analyzer is better ...

05-13-2014 08:26 AM

34crealock

Re: AIS / Marine Traffic

Thanks Dave. Do you suppose the software in the AIS is just coming up with wildly high SWR. I am not very electronic smart but I have never had so much trouble with plug and play.

05-13-2014 06:15 AM

SVAuspicious

Re: AIS / Marine Traffic

Quote:

Originally Posted by 34crealock

Talked to an engineer at Si-tex. Seems like you need an SWR on your antenna that is less than 5 to 1. Interference from metal near the antenna ( like on the pushpit)is a no no also. I hooked up to the mast head antenna and all is well. With a laptop plugged into the USB on the AIS you will get a readout on the current SWR after you get the fail light or after a few minutes if all is well. Seems like your vhf radio will T and R on a pretty lousy antenna.

There is no excuse for an VSWR as high as 5:1.

I'm not sure what "interference from metal near the antenna" means. There can be shielding and directive effects, but not interference. The near-field effects of metal near the antenna at the mast head and on the pushpit is not significant, absent "junk on the back."

Just because the equipment functions doesn't mean it is performing as you expect.

05-12-2014 04:41 PM

34crealock

Re: AIS / Marine Traffic

Talked to an engineer at Si-tex. Seems like you need an SWR on your antenna that is less than 5 to 1. Interference from metal near the antenna ( like on the pushpit)is a no no also. I hooked up to the mast head antenna and all is well. With a laptop plugged into the USB on the AIS you will get a readout on the current SWR after you get the fail light or after a few minutes if all is well. Seems like your vhf radio will T and R on a pretty lousy antenna.

05-12-2014 07:57 AM

34crealock

Re: AIS / Marine Traffic

I tried installing a class B ( Si Tex) and am having problems with the vhf ant also. It starts up fine, has good GPS signal, sends first location with mmsi # and then goes to fail mode(ais ant). I have a new dedicated ant on the pushpit and even hooked up a spare with a new cable. This is the second black box I have tried and both vhf ants work fine with voice comm. where to now?

05-12-2014 06:23 AM

SVAuspicious

Re: AIS / Marine Traffic

Quote:

Originally Posted by SteveInMD

I did ask a few boats if they could see me on their AIS. All said they could, so I guess it's working as it should. One said my data was not populated in the system, but I think that was due to my single antenna / splitter setup. They called me back a few minutes later and said all the data was there now.

That should not have anything to do with the splitter unless you were spending a lot of time talking on your VHF after you powered up. Static data (IIRC) for Class B is only sent every six minutes, and if you're talking on the VHF the splitter will block the AIS transmission.

05-11-2014 08:48 PM

SteveInMD

Re: AIS / Marine Traffic

Quote:

Originally Posted by SVAuspicious

If you like we can schedule a time to meet up and I'll put an antenna analyzer on your system for you.

Thank you. I may take you up on that at some point.

FWIW...

I was being picked up sporadically on MarineTraffic and aprs.fi this weekend. Both sites listed K3ARS as the source. K3ARS is in Chestertown, MD which is 24 NM from my slip. As far as I can tell this is the closest base station to Annapolis. It's no wonder that I don't show up consistently. At that range I'm surprised I show up at all.

I did ask a few boats if they could see me on their AIS. All said they could, so I guess it's working as it should. One said my data was not populated in the system, but I think that was due to my single antenna / splitter setup. They called me back a few minutes later and said all the data was there now.

My VSWR was showing up in ProAIS2 as 1.1:1.

I may add a second antenna some day, but what I have is going to have to be good enough for a little while.

05-10-2014 08:11 AM

SVAuspicious

Re: AIS / Marine Traffic

Quote:

Originally Posted by SteveInMD

Well everything else is working and their wiring is neat and orderly. Prettier than I could / would have done. Hopefully the quality is there too.

I apologize if I came across as snarky. I worked on three boats last week that needed significant re-wiring to get installed systems to work reliably. On one boat I pulled out 400 feet of wire abandoned in place.

The AIS 650 runs at the Class B specified power output. The moderator response has a typo - there is no such thing as a VSWR of 0.8:1. 1.0:1 is perfect. The AIS 650 will shut down to protect itself with a VSWR somewhat above 2.0:1. Note that the original poster found an installation problem that resolved the issue.

Quote:

Originally Posted by SteveInMD

I have the AIS100 splitter. My antenna is on top of the mast. I'll check the VSWR with the ProAIS2 app this weekend.

I'm not a fan of splitters. I encourage my customers to avoid them. You will have a 3 dB reduction (1/2 power) through the splitter and a small additional reduction due to the additional number of connectors - bigger yet if cheap crimp connectors are used. The signal reduction applies to your VHF as well as to the AIS.

If you like we can schedule a time to meet up and I'll put an antenna analyzer on your system for you.

You can certainly get systems with splitters to work (I have). My basic recommendation is to leave the masthead antenna to the fixed VHF and put another antenna on the pushpit rail, on a spreader, or an arch. My AIS antenna is on a radar pole. I only use solder-solder silver-teflon connectors and the best coax I can get.

05-09-2014 08:22 PM

SteveInMD

Re: AIS / Marine Traffic

Quote:

Originally Posted by SVAuspicious

*bites tongue* *hard*

Well everything else is working and their wiring is neat and orderly. Prettier than I could / would have done. Hopefully the quality is there too.

Quote:

Originally Posted by SVAuspicious

Possible. I'm surprised those town houses block anything. They are pretty lightly constructed.

Agreed. That's why I'm surprised I'm not being pick up on the websites. But then again Bernadette isn't either.

Quote:

Originally Posted by SVAuspicious

You can also look at MarineTraffic.com (10-15 minute delay) or aprs.fi (2 or 3 minute delay) on a smartphone.

I've been using the MarineTraffic app on my phone to see if I'm showing up. I didn't know about the delay.

Quote:

Originally Posted by SVAuspicious

You can't tell for sure. If you hear sqaucking on 87B or 88B try pulling the antenna connector off your radio (don't transmit) and see if you still hear it, although you may still hear Bernadette.

Note that aprs.fi lets you look at data up to a week old, so even if you don't talk to anyone you can get a pretty good idea of whether you are transmitting or not.

You aren't in silent mode are you? Within 5 minutes of power-on the indicator should be green. If it is blue you are in silent mode.